Mercury switch



Oct. 13, 1931. P. K. cRAMBLET MERCURY SWITCH Filed Nov.

lNDENTOR.

ATTORNEU.

Patented Oct. 13, 1931' UNIT-ED Is'r'ATi-:s PATENT OFFICE raux. x. Gamma?, or MILWAUKEE, wisconsin, AssIGNon, BY u usNE assremrmws,

TO MINNEAPOLIS-HONEYWELL REGULATOR SOTA., A `COIBEORATIGIN' OF DELAWARE COMPANY, F. MINNEAPOLIS, MINNE- MERCURY SWITCH This invention relates in general to mercury switches and more particularlytoza mercury switch of the type having an outer envelope. and an inner protective element of arc resisting material which receives the direct shock of the arc and interposes its-protective structure lbetween the destructive forces setup by the arcing and the outer envelope thereby prolonging the life of the 1o switch. l

One of the principal objects of the present invention resides in the provision of a novel protective element which is constituted of comparatively inexpensive material and A adapted to be readily and easily constructed and assembled with the switch thereby reducing the cost of manufacture.

Another object 's to provide a mercury switch having a. protective element of thisL 20 character' which is supported in proper position in the switch in a novel and e'ective manner which not only lends itself to convenient and economical manufacture but which also provides construction.

In carrying out the present invention amer'cury switch is provided which has an outer envelope which may be, constituted of' soft glass or other comparatively inexpensive material suitable for this "purpose, Within thel envelope .a protective element is provided and preferablyL is. constituted-of molded aluminum oxide, which. while inexpensive, may be readily wetted and' molded into any one of the variety of shapes or structures. Preferably the aluminum oxide is shaped to provide a plurality of spaced wells and has an intermediate -portion between such wells designed to coact with'agretaining element ,up under the high temperatures and rapid temperature fluctuations incident to the arclng without any impairment of its 'structure claims, lreference being had to the accompanya reliable and durable switch which also co'acts with the envelope to holdor of its desirable qualities. Further, even when in contact with the outer envelope in theassernbly it will not tend to fracture or break down the switch structure in use. However, many ofthe advantages oftheinvention may be realized by constituting theprotective element of various other arc resisting substances such as porcelain, quartz, hard glass, or the like.

Other objects and advantages reside in certain novel features ofthe construction, ar rangement and combination of parts which will be hereinafter more fully described' and particularly pointed out in the. appended 05 ing drawings forming a part of this specification, and in which Figure 1 is a plan viewpof the interior construction of a mercury switch embodying the present invention, the outer. envelope being shown in horizontalsection;

Figure 2 is a view in transverse vertical section on line 2-2 of Figure 1,;

Figure 3 isa view in central vertical longi# tudinal section showing the mercury switch of Figures 1 and 2 and illustrating the switch tilted to one extreme position; t

' Flgure 4 .is a similar view showing the switch tilted in its other extreme position;

. Flgure 5)-is a view indiametrical vertical section illustrating another form of mercury switch embodying the invention; and

lgure 6 is a view in horizontal cross section 'taken on line 6-6 of Figure 5.

Referring to the drawings'and more par ticularlv to Figures 1 to 4, inclusive, the numeral 1 designates an outer envelopewhich may be constitutedof soft glass or other suitable material. Within the outer envelope a protectivel element -designated generallyv at 2 is I crovitledv and is preferably constituted of aluminum oxide or-a mixture of aluminum oxide and vsilicon oxide known to the trade als alundum. Insome instances" such a mixture also includes a suitable binding' material but of course when subjected tothe action ofheat the aluminum and silicon -oxide alone will harden or Set. lThe alummunr oxide or the .mixture containin sanreis wetted and molded to the shapesh wnl-*a'nd baked or-heated um to cause it to set and harden prior to its assembly with the switch and, as shown, is so formeduas to have spaced wells 3 and 4 disposed at the ends of an integral connecting or base portion 5. rllhe wells 3 and 4 are ot cylindrical form, although they merge into their integral connecting portion 5 and as illustrated, they are open at the top and closed at the bottom. The base of the protective element, that is, the lower portion of its periphery is rounded as at 2 to conform to the curvature of the inner wall of the envelope against which it is engaged (see Figure 2). The confronting portions of the wells 3 and 4 have slots 6 providing a lip orvsuri'ace 6 located within the protective structure of the well and adapted to receive the arc. By having theseslots 6 extend only through that portion of the well which is directly alined with the connecting portion/of the protective element (s'ee Figure 1), the upper extremity of eacli well is interposed between the arcing zone and the adjacent wall of the outer envelope (compare Figures 1 to 4` inclusive).

For the purpose of holding the protective element in position in the outer envelope,` a retaining or holding element 7 is rprovided and consists of a split ring of resilient metal preferably stainless yferreous metal such as stainless steel 0r stainless iron. As illustrated, in Figure 2, the retaining element 7 is not ot' true circular form but has a flat portion 7a to engage the tlat upper surface of the connecting portion ofthe protective element.

Beyond the flat portion 7 a the retaining por- P tion has arcuate portions 7b which t snugly up against and have gripping engagement with the inner peripheral wall ot the outer envelope; With this construction the retaining. element lpresses the protective element firmly against the outerl envelope and due to the frictional engagement between the outer envelope, the retaining element and the protective element. the protective element is irmlv held in position in the assembly.

` A body ot mercury designated at 8, is provided in the outer envelope and has portions 8a and 8b 'filling the wells 3 and 4` respectively, and also has a shittable portion 8 intermediate the wells and alternately making and breaking contact with the portions 8a and 8b of the wells over the lips 6 ot the wells. Electrodes 9 and 10 are sealed through the upper portion ot the outer envelope and project down into the wells 3 and 4. For practically their entire extent within the outer envelope the electrodes 9 and 1() are shielded bv sleeves 11 of glassor other suitable material but the lower extremities of the electrodes are eXposed and are bent at right angles to hold the shields in place. A third electrode 12 is sealed through one end ot the outer envelope and curves around one ot the wells of the protective element and is constantly imtective element the Leaaova mersed in the shiftable portion 8c of the mercur lili the form of the invention shown in Figures 5 and 6, a rotary type of switch is shown and comprises an outer envelope 15 of soft glass or other suitable material. Within the outer envelope a protective element designated generally at 16 is provided and as before is constituted of molded aluminum oxide or alundum. In this embodiment the shape and structure of the protective element is somewhat different from that of the previous embodiment and as illustrated the protective element has a plate-like base'or connecting portion 17 and integral wells 18 arranged in circular series and having their axes inclined toward the center tube so that the outer portion ot the top of each well is higher than the .portion nearest the center, thus, interposing between the arcing zone and the outer envelope is a wall of protective material. A body of mercury generally designated at 20 is provided in the outer envelope and has portions 2Oa filling the wells 18 and a shiftable portion 20'b adapted to make and break contact with the'portions in the wells when the switch is operated. In this form of the invention the protective element is held in position in the outer envelope by virtue of the engagement of its periphery with the inner wall of the envelope and by virtue of the action of one of the electrodes designated generally at 21 and consisting of two strands of wire sealed in through the upper part ot the envelope and assing down through the center of the plate element. Below the prostrands of the electrodes 21 are extended away from each other and radially ofthe plate 17 as indicated at 21a and have their terminals 2lb bent up into peripheral notches in the plate 17. A shield 17 ot the protective A22 consisting of a glass sleeve covers the elecare also provided tor the electrodes 23 and prevent direct contact between the portion ot the electrodes 23 above the wells and the shiftable portion of the mercury. rThis type of switch is preferably mounted andv operated in the manner fully set forth in the application ot Paul K. Cramblet for mercury switch and operating mechanism therefor, filed November 24, 1928, Serial No. 321,566,v although. of course, any suitable operating mechanism mav be used in lieu thereof.

ln both forms of the invention an easily shaped protective element is provided and has spaced \wells over the lips of which the mercury to mercury make and break occurs. The Wells and the entire structure of the protective element may be completed prior to lio ing the arcremains unimpaired and will not become slotted or disintegrated in any fashion. Further, a protective element so constructed and so constituted absorbs the shocks and strains of arcing without transmitting them to the envelope in such a way as t'obreak down the envelope or otherwise impair the structure ofthe switch.

The invention claimed is:

1. A mercury switch including an outer envelope, an inner protective structure of molded arc resistant material and having a yperipheral portion engaged with 4the lower portionl only of the inner walll of the outer envelope', a resilient ring like metallic retaining element interposed between and coacting with the upper portion of the-envelope and with the upper portion of the protective structure to complete the holding of the protective structure in proper position in the envelope, and a body of mercury in said envelope and having portions making and breaking contact on a surface of the protective structure.

2. A mercury switch comprising an outer envelope, an inner protective structure 'of' molded arc resistant material smaller than the outer envelope and having a base portion engaging a portion only of the inner wall of the outer envelope and also having a well l formed therein and provided with an open end in spaced relation to the inner wall of ihe outer envelope, a resilient and flexible metallic retaining element interposed between and coacting with the protective structure and with a spaced and opposed' portion of the inner wall of the outer envelope-to hold the protective structure in properposition in the envelope, and a body of mercury having a portion filling the well and a portion'outside of the well and making and breaki-n conjtaclt1 with the portion of the mercury 1n the we 3. A mercury switch comprising an outer envelope, an inner protective structure of molded arc resisting material including Pspaced wells and an integral connecting portion, and a split metallic retaining ring coacting with thec'onnecting portion of the protective element for'holding the protective y' element in position.

4. A mercury swltch comprlslng an -outer envelope, an lnner protectlve structure of arc nature.

split approximately ring-like structure engaging the envelope and the intermediate portion of the protective element for holding the protective element engaged with the outer envelope and against displacement relative thereto.

5. A mercury switch .comprising an outer envelope,` an inner protective struct-ure `of arc resisting material including a well having a closed bottom and an open top and having a slot in the top over the ioor of which the make and break occurs.

6. A mercury switch comprising an outer envelope, an inner protective structure of molded arc resisting material smaller than the outer envelope and' having a base portion engaging a portion only of the inner periphery of the outer envelope and having a well integral with the base portion and formed with an open end in spaced relation to the innerv Wall of the ou er envelope, vieldable means interposed between and coactig with the upper portion of the outer envelope and with the base to hold the protective structure l in proper position in the envelope and a body of mercury having a portion filling the Well anda portion around the protective structure and making and breaking contact with the portion in the well over a lip of the well.

7 A mercury switch comprising an outer envelope, an inner protective structure'of arc resisting material including a plate like body and a series of wells integral with the plate like body and having open ends, the wells being arranged at spaced angular intervals varound-the envelope, and a body of mercury having portions filling the wells and a shiftable portion making and breaking contact with the portions in the wells. i

8. A mercury switch comprising an outer envelope, an inner protective structure of arc resisting material including a plate like body and a series of wells 'integral with the late like body and having open ends, the wel s b eing arranged at spacedv angular intervals around the envelope, and a body of mercury having portions filling the wellsand a shiftable portion making and breaking conta-ct with the portions in the wells, an electrode coacting with the plate like body to hold the y yieldable retaining element in the form of a protective structure in position and constantly immersed in the shiftable portion of the mercury, and electrodes sealed through the outer envelope and' projecting down into the wells.

In Witness whereof, I hereto affix my sig- PAUL K. CRAMBLET.

resisting material having'spaced' wells and a I 

